NDATA Section

Fields containing data to be indexed for name searching can be specified exclusively by adding NDATA sections to section groups of type: BASIC_SECTION_GROUP, HTML_SECTION_GROUP, or XML_SECTION_GROUP.

Users can synthesize textual documents, which contain name data, using two possible datastores: MULTI_COLUMN_DATASTORE or USER_DATASTORE. The following example uses MULTI_COLUMN_DATASTORE to pick up relevant columns containing the name data for indexing:

create table people(firstname varchar2(80), surname varchar2(80));
 insert into people values('John', 'Smith');
 commit;
 begin
   ctx_ddl.create_preference('nameds', 'MULTI_COLUMN_DATASTORE');
   ctx_ddl.set_attribute('nameds', 'columns', 'firstname,surname');
 end;
 / 

This produces the following virtual text for indexing:

<FIRSTNAME>
John
</FIRSTNAME>
<SURNAME>
Smith
</SURNAME>

You can then create NDATA sections for FIRSTNAME and SURNAME sections:

begin
  ctx_ddl.create_section_group('namegroup', 'BASIC_SECTION_GROUP');
  ctx_ddl.add_ndata_section('namegroup', 'FIRSTNAME', 'FIRSTNAME');
  ctx_ddl.add_ndata_section('namegroup', 'SURNAME', 'SURNAME');
end;
/

Then create the index using the datastore preference and section group preference created earlier:

create index peopleidx on people(firstname) indextype is ctxsys.context
parameters('section group namegroup datastore nameds');

NDATA sections support both single- and multi-byte data, however, there are character- and term-based limitations. NDATA section data that is indexed is constrained as follows:

• the number of characters in a single, white space delimited term

  511

• the number of white space delimited terms

  255

• the total number of characters, including white spaces

  511